Method of manufacturing turbine blades



June 18, 1929.

WITNESSES E. F. MILLER METHOD OF MANUFACTURING TURBINE BLADES Filed Nov. 50, 1927 INVENTOR EEMiller BY \l-PLM ATTORNEY Patented June 18, 1929.

1,718,061, PATENT' OFFICE.

ERNEST F. MILLER, OF MOORES, PENN SYLITAN IA, ASSIGNOR T WESTINGHOUSE ELEC- TRIO & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

un'rnon or nanuracrunme TURBINE BLADES.

Application filed November 80, 1927. Serial No. 236,869.

My invention relates to blading for elastic fluid turbines and it has for an object, to impr'ove the construction of such blading and also themethod of manufacture thereof.

In view 'of the relatively large stresses which are set up due to centrifugal force, it

f larger reaction blades, for with a given contour the hollow construction not only reduces the masswhich is subject to centrifugal force, but it'is alsowell adapted to withstand various bending stresses which occur in the operla ation of a turbine.

. Furthermore, a more rigid construction for a given weight can be produced it the walls of a hollow blade are not of uniform thickness, but rather of greaterthickncss in the vicinity of-the thinner edge portions of a blade. A construction of this type results in the disposition of relatively greater quantities of metal at great distances from the shorter transverse axis and thus, gives a blade considerable strength with respect to this axis, while at the same time, suflicient metal is disposed in the front and back walls to assure sufficient strength about the longer transverse axis. This thicker inlet and outlet edge portions are also a 1vantageous, as these edges are subject to the greatest erosion. Moreover, a blade should be of simple construction so that it may be made with as few operations as possible andthus, be inexpensive to manufacture.

More particularly, therefore, an ob'ect of my invention is to provide a blade 0 light, and yet rigid construction, and which shall be inexpensive to manufacture, and to provide an improved method of making the Same.

Apparatus exemplifying-the features of my invention is shown in the accompanying drawings, forming a part of this specification', and wherein:

Figs. 1 and 2 are transverse sections ofa blank, showing the manner in which different,

operations are performed thereon;

Fig. 3 is a transverse section of a' blank on which the preliminary operations have been completed; and, l

Fig. 4 is a transverse section of a completed blade.

According to my invention, a suitable solid bar section, or blank 10, which is, preferably, a forging having substantially the exterior configuration of a finished blade, is cut lengthwise from end to end by suitable apparatus, such as the milling cutter 11, so as to form a longitudinally extending groove, or channel 12. in the blank. An end miller 13 is then run down the length of the blank 10, the shank of the miller 13 extending through the groove 12, as shown in Fig. 2. The completion of these operations leaves the blank 10 substantially as shown in Fig. 3. A strl 14, of a length corresponding to the lengt of the blank 10, is then fitted into the groove 12 and is secured to the remaining portions of the side walls of this roove in any approved manner, preferably by means of silver solder. This operation completes the blade, except in so far as polishing, and like operations.

In this way, a hollow blade may be formed from a solid forgin or the like, by performing only two re at-ively simple cutting operations. While the groove 12 may be cut 1n either the front or the back of the blade section 10, I prefer to cut this groove in the back as shown'a's the back of the blade is less subject to the effects of erosion than the While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited,but is sus-' ceptible of various changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are iniposed by theprior art or as are specifically set forth in the appended claims.

-- What I claim is:

'1. The method of producing a hollow impeller blade from a solid blank which comprises slotting the blank, undercuttin the' walls of the slot and then closing the s 0t.

-2. The method of producing a hollow impeller blade from a solid blank which comprises cutting a slot in a convex surface of the blank, undercuttin the walls of the slot and then closing the s ot.

3. The method of producing a hollow im-'- ting away suflicient portions of the walls of prises cutting a channel in the blank, cutting away suliicient portions of the Walls of the channel to leave side walls of suitable thickness for a blade, fitting a strip of material to remaining portionsof the side walls of the channel for clos ng the same and securing the litted strip to the remaining portions of said side walls by fusion of metal.

5. The method of producing a hollow impeller blade'froin a solid blank which coinprises cutting a channel in the blank, removing sufiicient portions of the side walls of the channel to leave front and back walls of suitable thickness and to leave a relatively greater thickness of material in the vicinity of the junctureof these walls and fitting a strip to the runaining portions of the side walls of the channel for closing the same.

In testimony whereof, I have hereunto subscribed my name this 22nd day of Nov., 1927.

ERNEST F. MILLER. 

